[Circulating immune complexes in a population of subjects seropositive for rheumatoid factor]

The level of immune complexes has been detected with the C1q binding test in 179 subjects positive by Latex agglutination test (titre greater than 1/20). The average of C1q binding was 5.36%, significantly higher than in 30 normal blood donors. A positive correlation was observed between the percent of C1q binding and, respectively, the titre of the latex test and the erythrocyte sedimentation rate. Of the 36 patients with rheumatoid arthritis, 16 (45.7%) showed an high level of C1q binding activity (greater than 5%), as well as 4 of the 8 patients with chronic hepatitis (50%) and 11 of the 31 patients with infectious diseases. No immune complexes were detected among the 11 healthy latex positive subjects.